The electronics fabrication industry typically requires ultra clean surfaces in fabrication areas, such as clean rooms, due to the extremely small electrical lines and devices and the density of lines and devices that are currently demanded by customers of electronic circuits, such as integrated circuits, typically found in computer chips and memory devices.
Electronic fabrication industry machines and surfaces surrounding the machines and work areas are typically cleaned by wiping down the surfaces with towels, wipes and wipes prewetted with various solvents, wetting agents and cleaning solutions.
Solutions of isopropyl alcohol (IPA) in water have been used to provide the necessary wetting for efficient cleaning of clean room equipment and surfaces such as benchtops. The solutions leave no residue and provide surface tensions of about 45 dynes/cm at ˜6 wt % IPA. Although these solutions perform well, the semiconductor industry is under increasing pressure to reduce the emission of volatile organic chemicals (VOC's).
The intense pressure to reduce VOC emissions is of relatively recent origin. U.S. Pat. No. 4,328,279 describes the use of completely non-volatile anionic and nonionic surfactants to enhance the wetting of the fibers in a cleaning wipe. These surfactants would be expected to leave a residue on a cleanroom surface.
Acetylenic alcohols and glycols have been reported to be effective as additives in cleaning mirrors and lenses in the presence of relatively large amounts of a lower alcohol, such as ethanol and ammonia, see U.S. Pat. No. 4,054,534.
A similar solution was found to be effective for cleaning photoreceptors, as described in U.S. Pat. No. 3,979,317.
U.S. Pat. No. 3,728,269 describes the use of a mixture of a series of alcohols, including small amounts of 3,5-dimethyl-1-hexyn-3-ol, for cleaning surfaces.
Similarly, U.S. Pat. No. 4,689,168 describes the use of solutions containing 3,5-dimethyl-1-hexyn-3-ol, along with other surfactants in a hard surface cleaning formulation. This disclosure specifically states that the cleaning solution must form an emulsion on agitation.
U.S. Pat. No. 3,819,522 describes the use of ethoxylated acetylenic glycols in anti-fogging window cleaners, which require an anionic sulfate to make the glycol acceptable.
Austrian Patent 257,015 (Chemical Abstract 67:118464) discloses the use of 3,5-dimethyl-1-hexyn-3-ol, along with an amine and non-volatile surfactant for cleaning glass.
Finally, a technical article discusses evaluation of solutions low- and non-volatile organic compounds as replacements for high VOC cleaning formulations in clean rooms; Chemical Abstracts 121:159750, Allison et al., Characterization of Low and Non Volatile Organic Compound Containing Cleaners for Cleanroom Work Surfaces, 1st Int. SAMPE Environ. Conf., May 21–23, 1991.
Acetylenic alcohols are known surface active agents as described in U.S. Pat. No. 4,117,249.
Ethoxylated acetylinic glycols are disclosed in U.S. Pat. No. 5,650,543 as being effective surfactants.
Additional references of interest include: U.S. Pat. Nos. 4,847,089; 4,931,201; 5,259,993; 5,389,281; 5,466,389; 5,650,543 and 6,017872.
The prior art has attempted to provide an effective clean room wipe, such as represented by U.S. Pat. No. 4,328,279, but has failed to achieve low VOC, low nonvolatile residue (NVR), while avoiding the effects of detergency (foaming), in providing an effective prewetted wipe meeting the criteria of the electronics fabrication industry and the requirements of municipal and national environmental regulations on emissions of various organics. The present invention overcomes the drawbacks of the prior art and achieves the requirements of the electronics fabrication industry and municipal and national environmental regulations in a novel prewetted wipe having unexpected superior performance as will be set forth in greater detail below.